Discuss whether any work is being done by each of thefollowing
agents and if so, tell whether the work is positive
ornegative?
(a) a chicken scratching the ground
(b) a person studying
(c) a crane lifting a bucket of concrete
(d) the force of gravity on the bucket in part (c)
(e) the leg muscles of a person in the act of
sittingdown.

Explained

Explanation:

a) the work done will be positive since the chicken is scratching the ground. Here displacement is along the direction of force.

b) A person studying does no work in the language of physics because there is no displacement.

C) the work is done on the bucket by the crane and work is positive and here the displacement is in the direction of force.

d) Gravitational force act on the bucket in downward direction, here the work done will be negative as the force displacement are opposite to each other.

E)Negative work will be done as the force applied  by the muscle is in opposite to the displacement.

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement